The present invention relates to an electrode member for a plasma treating apparatus to be attached to the front surface of the gas supplying port of an electrode for plasma generation in the plasma treating apparatus. Further, the present invention relates to a plasma treating apparatus and plasma treating method using the above-mentioned electrode member.
As an apparatus for surface finishing an electronic component such as a substrate or a semiconductor device, a plasma treating apparatus has been known. The plasma treating apparatus serves to generate plasma under a vacuum atmosphere and to carry out a treatment such as etching over the surface of an object to be treated physically and chemically by the plasma. The plasma is generated by applying a high frequency voltage to an electrode in a sealed treatment chamber. A gas for plasma generation having a predetermined pressure (hereinafter referred to as a “gas”) is supplied in the treatment chamber.
In such a plasma treatment, in some cases it is desirable that a high density plasma should be generated depending on the purposes of the treatment. In a plasma treating apparatus for carrying out plasma etching on a silicon substrate, such as a semiconductor wafer, a method of spraying and supplying a gas having a comparatively high pressure onto the surface of a silicon wafer is used in order to enhance the treatment efficiency.
For such a gas supplying method, a conventional method is known in which a gas supplying port is formed on an upper electrode provided opposite to a lower electrode holding a silicon wafer. The upper electrode serves as a discharge electrode plate and a gas introducing plate. In this case, the discharge electrode plate has a large number of fine gas supplying holes and is attached to the upper electrode, thereby uniformly supplying a gas to the surface of a silicon wafer.
In the case in which the discharge electrode plate is used, however, there are the following problems. In the method of injecting and supplying a gas from a gas supplying hole, the uniform distribution of the gas to be supplied is restricted and the amount of the gas to be sprayed onto the surface of a silicon wafer is not uniform between a portion provided under the supplying hole and other portions.
For this reason, an abnormal discharge in which plasma is convergently generated in the vicinity of the supplying hole is apt to be induced and various drawbacks are caused by the abnormal discharge. More specifically, etching is convergently carried out in a portion in which the abnormal discharge is generated. Therefore, there is a drawback in that the quality of etching is affected, for example, a silicon wafer is damaged or an etching result has a variation. In addition, there is a drawback that a discharge electrode plate provided with the gas supplying hole is worn by the plasma, depending on the material of the discharge electrode plate.
Moreover, porous ceramic having crystal grains, having a diameter of about 10 μm to 50 μm, aggregated and sintered has been tried to be used as a discharge electrode plate. However, since the discharge electrode plate is easily broken due to heat shock caused by the heat of plasma, it cannot be used as a discharge electrode to be directly exposed to the plasma.